Supporting a generic Nitrogen-to-protein Conversion Factor (NCF) of 5.0 for algae species in international standards in absence of scientifically established specific values

Algae products have the potential to partially fulfill the growing demand for non-animal protein sources, and the volume of algae products used in food and feed applications is rising. Accurate determination of the protein content in algae is important to assess their nutritional value, ensure compliance, and facilitate harmonized trade. The most implemented method is based on the determination of nitrogen followed by its conversion into protein through a Nitrogen-to-protein Conversion Factor (NCF). In this paper, we extend the meta-analysis published by Angell in 2016 with data from six other studies to reach a dataset of 174 entries. This extended dataset confirms the high variability observed for NCFs in algae and supports the use of a generic NCF of 5.0 for algae species in international standards in absence of scientifically established values for a given species and growth conditions. • Meta-analysis of 174 data entries on nitrogen-to-protein conversion factors in algae. • Confirms wide variability between species and growth conditions. • Demonstrates that generic NCF of 6.25 significantly overestimates protein content in algae. • Recommends a generic NCG of 5.0 for algae in absence of species-specific data. • Supports harmonization of international standards for algae-based products.